1. Technical Field
The present invention relates to a communication apparatus communicating information, and a communication method.
2. Related Art
Conventionally, an information system is known which is installed in each automobile and is mainly configured with a communication apparatus transmitting and receiving information by inter-vehicle communication to obtain and indicate information on a traffic situation around the own vehicle (e.g. refer to JP-A-2008-245268).
Each communication apparatus configuring this type of information system obtains information on behavior of the own vehicle (hereinafter, referred to as own vehicle information) from various sensors and transmits the information. The communication apparatus receives information on behavior of another vehicle (hereinafter, referred to as other vehicle information) from a communication apparatus installed in the other vehicle. In addition, the communication apparatus indicates the presence of another vehicle having a possibility of colliding with the own vehicle, as a traffic situation around the own vehicle, on the basis of the own vehicle information and the other vehicle information.
According to the information system described above, the information recognized by the communication apparatus (i.e., other vehicle information) is required to be updated along the time axis and to correspond to actual behavior of the other vehicle.
Hence, a communication apparatus configuring an information system is proposed which, if other vehicle information received from a communication apparatus installed in another vehicle represents the other vehicle traveling at a speed higher than that of the own vehicle, promptly returns own vehicle information, and increases the frequency of transmitting the own vehicle information (e.g. refer to JP-A-2010-288141).
As described above, if the frequency of transmitting the own vehicle information is set higher, the own vehicle information corresponding to the actual behavior of the vehicle can be transmitted. However, communications traffic becomes heavy. If the communications traffic becomes too heavy, communication quality can deteriorate due to collisions between signals transmitted from the communication apparatuses.
That is, according to the conventional communication apparatus, it is difficult to make another communication apparatus recognize information corresponding to the actual behavior of the vehicle while suppressing the increase of communications traffic.